Sleeve valve oil seal

ABSTRACT

Leakage of a liquid (e.g. a coolant and/or a lubricant) past a sleeve valve to a port in communication with a combustion chamber of an internal combustion engine can be prevented by use of a substantially ring-shaped seal, which can be carried on the sleeve valve or disposed on a stationary part of the internal combustion engine.

CROSS-REFERENCE TO RELATED APPLICATION

The current application is claims priority under 35 U.S.C. §119(e) toU.S. provisional application No. 61/837,101 filed Jun. 19, 2013, thedisclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The subject matter described herein relates to engines that include oneor more ports controlled by the motion of one or more sleeve valves.

BACKGROUND

A sleeve valve is a type of valve usable in internal combustion engines,including but not limited to opposed piston engines in which two pistonsshare a single cylinder, and also in engines in which each pistonreciprocates in its own cylinder. Such a valve typically forms all or aportion of the cylinder wall defining a combustion chamber inside thecylinder. In some variations, one or more sleeve valves can reciprocateback and forth substantially in parallel to an axis upon which one ormore pistons reciprocates to open and close intake and/or exhaust portsat appropriate times to introduce air or an air-fuel mixture into thecombustion chamber and/or to exhaust combustion products from thechamber. In other variations, one or more sleeve valves can rotate aboutand/or translate along the axis of the piston or pistons to open andclose one or both of the intake and exhaust ports. Due to thepotentially large circumferential port area that can be controlled by asleeve valve, such valves can provide a relatively large cross sectionalarea for fluid flow in the open position.

Sleeve valves, in common with other parts of an internal combustionengine, especially those in the region of the combustion chamber,require cooling. This can be achieved by provision of oil to the sleevevalve, which enables heat arising in the sleeve valve as a result of thecombustion process, to be transferred away from the sleeve valve toother parts of the engine. If the oil is delivered to the exteriorsurface of the sleeve valve, it can transfer heat out of the sleevevalve to other, stationary parts of the engine. The oil can also act asa lubricant between the exterior surface of the sleeve valve and theengine block. However, leakage of the oil into the ports is a concern.

SUMMARY

The current subject matter relates generally to seals for preventingleakage of a liquid (e.g. a coolant and/or a lubricant) past a sleevevalve to a port in communication with a combustion chamber of aninternal combustion engine.

In one aspect, a sleeve valve assembly includes a sleeve valve and asubstantially ring-shaped seal. The sleeve valve has a valve bodyconfigured to at least partially encircle one or more pistons that movesin a reciprocating manner on operation of an internal combustion engine.The sleeve valve and the one or more pistons at least partially define acombustion chamber of the internal combustion engine, and the sleevevalve is configured to move between open and closed positions to controlfluid flow through a port that opens to the combustion chamber. Thesubstantially ring-shaped seal is configured to resist leakage of aliquid (e.g. coolant and/or lubricant) past the valve body to the port.In optional variations, the substantially ring-shaped seal includes atleast one of a) a ring carried in a groove recessed into the valve body,and b) first and second rings disposed around the valve body and biasedapart from each other. In option b), the first and second rings aredisposed on a stationary part of the internal combustion engine suchthat the valve body moves relative to the first and second rings.

In an interrelated aspect, a method includes moving a sleeve valvebetween open and closed positions to control fluid flow through a portof an internal combustion and resisting leakage of a liquid comprisingcoolant and/or lubricant past a valve body of the sleeve valve to theport. The resisting is performed at least in part by a substantiallyring-shaped seal that includes either or both of a) a ring carried in agroove recessed into the valve body, and b) first and second ringsdisposed around the valve body and biased apart from each other. Inoption b), the first and second rings are disposed on a stationary partof the internal combustion engine such that the valve body movesrelative to the first and second rings.

In other interrelated aspects an internal combustion engine includes thesleeve valve assembly discussed above with any of the optionalvariations discussed below. Alternatively or in addition, such aninternal combustion engine can be arranged to operate consistent withthe method discussed above optionally including any variations discussedbelow. A vehicle can include such an internal combustion engine.

In optional variations, one or more additional features, including butnot limited to those discussed in the next few paragraphs, can beincluded in implementations of the current subject matter. The ringand/or each of the first and second rings can be formed of a metal. Oneor more compression rings can be included in a sleeve valve assembly orotherwise be included for resisting leakage of gases in the combustionchamber and/or the port past the sleeve valve. The sleeve valve canreciprocate between the open and closed positions along a common axiswith a piston of the one or more pistons. The valve body can include acylindrical body having a length and a flange spaced apart radiallyoutwards from the cylindrical body and extending along at least a partof the length, and the cylindrical body and the flange can define acavity therebetween in which the liquid can circulate. The seal canoptionally be carried by the flange.

Consistent with option a), the substantially ring-shaped seal caninclude the ring carried in the groove recessed into the valve body, andthe seal can exert a radial force outward against the stationary part ofthe internal combustion engine. The seal can exert a first force againsta first side of the groove and a second force against a second side ofthe groove. The seal can include a biasing structure that exerts thefirst and second forces. The seal can include both the ring and anadditional ring, and the ring and additional ring can be substantiallyflat, split rings. The ring and the additional ring can be separated bythe biasing structure. The groove can be configured such that thematerial thickness of the valve body is substantially the same at thegroove as through a remainder of the valve body. The seal can remainsubstantially stationary relative to the valve body as the sleeve valvemoves.

Consistent with option b), the substantially ring-shaped seal caninclude the first and second rings disposed on the stationary part andaround the valve body, and the first and second rings can haverespective ring tensions to exert a radial force inward against thevalve body. The first ring and the second ring can be separated by abiasing structure which biases them apart. The first and second ringscan include flat, split rings having respective ring tensions arisingfrom one or more of their shape; size; curvature and material. Thestationary part can include a groove in which the seal is installed, andthe first ring can be biased against a first side of the groove whilethe second ring is biased against a second, opposite side of the groove.The stationary part can further include an oil drain through which oilin the groove drains. The sleeve valve body can include a honed surfaceagainst which the first and second rings exert the radial force.

The details of one or more variations of the subject matter describedherein are set forth in the accompanying drawings and the descriptionbelow. Other features and advantages of the subject matter describedherein will be apparent from the description and drawings, and from theclaims. The claims that follow this disclosure are intended to definethe scope of the protected subject matter.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, show certain aspects of the subject matterdisclosed herein and, together with the description, help explain someof the principles associated with the disclosed implementations. Itshould be noted that the orientation of various features or structuresillustrated in the drawings are not meant to be limiting. For example,in an engine with the axis or axes of reciprocation of the pistons lyingclose to horizontal, the structures in FIG. 3, FIG. 4, and FIG. 6, FIG.7, FIG. 8, FIG. 9 will be clearly understood to be rotated by some anglerelative to that depicted. In the drawings,

FIG. 1 shows a cutaway diagram of part of an internal combustion enginein which two opposed pistons move reciprocally within a cylinder;

FIG. 2 shows a cross-sectional diagram of part of the internalcombustion engine shown in FIG. 1;

FIG. 3A shows a diagram illustrating an example of a first sleeve valveand sealing mechanism consistent with implementations of the currentsubject matter;

FIG. 3B shows a diagram illustrating another example of a sleeve valveand sealing mechanism consistent with implementations of the currentsubject matter;

FIG. 4 shows a diagram illustrating an example of a second sleeve valveand sealing mechanism consistent with implementations of the currentsubject matter;

FIG. 5 shows a process flow diagram illustrating aspects of a methodhaving one or more features consistent with implementations of thecurrent subject matter;

FIG. 6 shows a diagram illustrating an example of a third sleeve valveand sealing mechanism consistent with implementations of the currentsubject matter, with the sleeve valve in a closed position;

FIG. 7 shows a diagram illustrating the third sleeve valve and sealingmechanism of FIG. 6, with the sleeve valve in an open position;

FIG. 8 shows a diagram illustrating a detail of the sealing mechanism ofFIG. 6 and FIG. 7;

FIG. 9 shows a diagram illustrating a detail of another example of asealing mechanism consistent with implementations of the current subjectmatter; and

FIG. 10 shows a process flow diagram illustrating aspects of a methodhaving one or more features consistent with implementations of thecurrent subject matter.

When practical, similar reference numbers denote similar structures,features, or elements.

DETAILED DESCRIPTION

Implementations of the current subject matter can, among other possibleadvantages, provide systems, methods, techniques, etc. to achieve alubricant seal between a sleeve valve and an engine block or other partof an internal combustion engine that remains stationary duringoperation of the sleeve valve. In particular, the efficacy of thelubricant seal is improved by provision of an improved sealing apparatusand/or a sealing apparatus that moves with the sleeve valve.

FIG. 1 shows a partially cut away isometric view of an illustrative butnon-limiting example of an internal combustion engine 100 in whichsleeve valve sealing as discussed herein can be applied. Sleeve valvesthat are sealed in a manner consistent with implementations of thecurrent subject matter can be used in opposed piston engines, includingconfigurations differing from the examples discussed herein as well asin other engine configurations in which a piston does not share acombustion chamber with one or more other pistons. In addition, thestructures and mechanisms for opening and closing sleeve valves that aredepicted in the drawings and described herein are only illustrativeexamples. Other approaches to controlling the operation of sleeve valvesin an internal combustion engine can be used in conjunction with thedescribed sealing techniques. Furthermore, in engines including morethan one sleeve valve, sealing approaches consistent withimplementations of the current subject matter need not be used on all ofthe sleeve valves. For example, an opposed piston engine with two sleevevalves might use the described sealing technology on either only one ofthe sleeves or on both of the sleeves controlling fluid flow into andout of the combustion chamber.

The internal combustion engine 100 includes a pair of opposing pistonsthat includes a first piston 102 and a second piston 104. The firstpiston 102 is operably coupled to a first crankshaft 106 by a firstconnecting rod 110 and the second piston 104 is operably coupled to asecond crankshaft 112 by a second connecting rod 114. As shown in FIG.1, the first crankshaft 106 is operably coupled to the second crankshaft112 by a series of gears that synchronize or otherwise control motion ofthe first piston 102 and second piston 104. During engine operation, thefirst piston 102 and the second piston 104 reciprocate toward and awayfrom each other in coaxially aligned cylindrical bores formed bycorresponding sleeve valves. More specifically, the first piston 102reciprocates back and forth in an exhaust sleeve valve 116, while thesecond piston 104 reciprocates back and forth in a corresponding intakesleeve valve 120. The exhaust sleeve valve 116 and the intake sleevevalve 120 can also reciprocate back and forth to open and close acorresponding exhaust port 122 and inlet port 124, respectively, atappropriate times during the engine cycle to deliver air and/or fuel toa combustion chamber 126 defined at least in part by the bodies of theexhaust and intake sleeve valves 116, 120 and the heads of the first andsecond pistons 102, 104.

FIG. 2 shows a cross-sectional view 200 of the internal combustionengine 100 of FIG. 1. As further illustrated in FIG. 2, a first pivotingrocker arm 230 (also referred to as a “rocker” 230), which has aproximal end portion in operational contact with a corresponding firstcam lobe 232 and a distal end portion operably coupled to the exhaustsleeve valve 116, opens the exhaust sleeve valve 116, for example bymoving a sealing edge of the exhaust sleeve valve 116 away from itscorresponding first valve seat 234. Similarly, a pivoting rocker arm 236(also referred to as a “rocker” 240), which has a proximal end portionin operational contact with a second cam lobe 240 and a distal endportion operably coupled to the intake sleeve valve 120, opens theintake sleeve valve 120, for example by moving a sealing edge of theintake sleeve valve 120 away from its corresponding second valve seat242.

The first cam lobe 232 can be carried on a suitable first camshaft thatcan be operably coupled to a corresponding crankshaft by one or moregears. On the exhaust side, for example, rotation of the first cam lobe232 can drive the proximal end portion of the first rocker 230 in onedirection (e.g., from left to right), which in turn causes a distal endportion of the first rocker 230 to drive the exhaust sleeve valve 116 inan opposite direction (e.g., from right to left) to thereby open theexhaust port 122. A similar action can occur on the intake side, whererotation of the second cam lobe 240 can drive the proximal end portionof the second rocker 236 in one direction (e.g., from right to left),which in turn causes a distal end portion of the second rocker 236 todrive the intake sleeve valve 120 in an opposite direction (e.g., fromleft to right) to thereby open the inlet port 124.

Each of the exhaust sleeve valve 116 and the intake sleeve valve 120 isurged into a closed position by a corresponding biasing member, such asfor example a first large coil spring 244 and a second large coil spring246, each of which is compressed between a flange on the bottom portionof the corresponding sleeve valve and an opposing surface fixed to thecorresponding crankcase. The first biasing member 244 urges the exhaustsleeve valve 116 from left to right to close the exhaust port 122 ascontrolled by the first cam lobe 232, and the second biasing member 246urges the intake sleeve valve 120 from right to left to close the intakeport 124 as controlled by the second cam lobe 240.

Due to their proximity to the combustion chamber, the sleeve valves cantypically become extremely hot during operation of the engine. Withoutprovision for cooling the sleeve valves, they could undergo damage anddistortion. To provide cooling, a coolant, cooling fluid, etc. (such as,for example, oil or the like), can be circulated to contact the sleevevalve. A cooling fluid path within the engine block, part of a sleevevalve assembly, etc. can enable oil to circulate either within or aroundthe sleeve valve, depending on the design of the sleeve valve. Someexamples of such cooling are described in co-owned U.S. patentapplication publication no. US2010/0212622A1, the contents of which areherein incorporated by reference. Regardless of the design of the sleevevalve, it can be desirable for some cooling fluid to flow around theouter surface of the sleeve valve, so that it can act additionally as alubricant between the outer surface of the sleeve valve and thestationary part of the engine against which it slides. The stationarypart can be a part of the engine block, a part of a fluid path-definingpiece, or some other engine structure that does not move with the sleevevalve or piston. A trade-off can exist between providing sufficientlubrication and avoiding leakage of cooling fluid past the sleeve valveinto the port which the sleeve valve opens and closes. Many prior artpiston engines used rotating sleeve valves, which were known to havehigh oil consumption due to cooling fluid being carried past the sleevevalve to the port by the rotational movement. A reciprocating sleevevalve, has many advantages, such as a better ability to controlcombustion timing, as described in co-owned U.S. Pat. No. 7,559,298, thedisclosure of which is incorporated by reference herein. However, themovement of a reciprocating sleeve valve can potentially cause someamount of the cooling fluid to be carried past the sleeve valve to theport.

To address these and potentially other issues with currently availablesolutions, one or more implementations of the current subject matterprovide methods, systems, articles of manufacture, and the like that mayimprove the sealing ability of sleeve valves in internal combustionengines. The following exemplary embodiments provide sealing mechanismsfor controlling leakage of the cooling fluid into the inlet or exhaustport which is opened and closed by the sleeve valve.

Since a reciprocating sleeve valve does not need to include an openingto align with the intake or exhaust ports, a “sliding seal” i.e. a sealthat is able to maintain substantially continuous contact with thesliding metal surface of the sleeve valve, can be used, hence enabling asubstantially uninterrupted seal. Some examples of such seals consistentwith the current subject matter will be described in the following.

FIG. 3A shows a sleeve valve assembly 300 illustrating featuresconsistent with one or more implementations of the current subjectmatter. A cross-section through a sleeve valve body 302 is depicted. Thesleeve valve body 302 is shown in a closed position, covering a port 306(which can be an intake port, an exhaust port, etc.). In this position,the sleeve valve body 302 forms a gas seal with a valve seat 304 at afirst end 308 of the sleeve valve 302. The first end 308 is proximal tothe valve seat 304. As shown in FIG. 3A, the first end of the sleevevalve includes a gas assist feature similar to those described inco-owned U.S. Pat. No. 7,559,298 and co-owned U.S. patent applicationpublication no. US2012/0085309A1, the disclosure of which isincorporated herein by reference.

The sleeve valve body 302 reciprocates to open and close the port 306,in a direction as indicated by an arrow 310. As noted above in referenceto FIG. 1 and FIG. 2, the reciprocating can be effected by any variationof valve operation mechanism, including but not limited to cams, rockerarms, biasing springs, hydraulic systems, and the like, in any feasiblecombination. The sleeve valve body 302 can be formed as a hollowcylinder having an inside surface 312 and an exterior surface 314 and alength extending in the direction of the arrow 310. A piston and acombustion chamber (not shown) are disposed in the interior 316 of thehollow sleeve valve body 302. In other words, the sleeve valve body 302at least partially encircles at least one piston and a combustion volumethat expands and contracts with motion of the at least one piston. Aportion of the exterior surface 314 of the sleeve valve 302 distal fromthe valve seat 304 can run against a cylindrical guide 318 disposedbetween this distal portion of the sleeve valve and a stationary part320, which can be the engine block or other engine structure relative towhich the sleeve valve body 302 moves.

The proximal end 308 of the sleeve valve can include a flange or lip 322spaced radially outward from the sleeve valve body 302. A cavity 324 canbe formed in the space between the exterior surface 314 of the sleevevalve body 302 in the region of its proximal end 308 and the flange 322.The flange 322 can extend a sufficient distance along the length of thesleeve valve body 302 to cover the port 306 and to enable formation of aseal against the stationary part 320. The flange 322 forms the exteriorsurface of the sleeve valve in this region of the sleeve valve andpartially surrounds the sleeve valve body 302. This part of a sleevevalve can be referred to as an “umbrella” structure. The end of theflange 322 distal from the proximal end 308 of the sleeve valve body 302can include a groove 325 formed in the exterior surface of the flange322. The depth of the groove 325 can be such that it can accommodate aseal 326, details of which are described below. The groove 325 can beformed in an end region 327 of the flange 322, although it is notessential for the groove to be at the end of the flange 322. The endregion 327 can, in some implementations of the current subject matter,be formed as a lip protruding towards the inner surface 312 of thesleeve valve body 302, such that the material thickness of the flange322 in that region can be substantially the same as the thicknesselsewhere, while forming the groove 325. There is nevertheless a radialspace between the groove 325 and the guide 318.

The stationary part 320 has features enabling cooling fluid to becirculated through or in contact with the sleeve valve body 302. Thiscan be achieved by a variety of designs, for example an oil-pathdefining piece for circulating oil as a cooling fluid such as isdescribed in U.S. Pat. No. 7,559,298. Schematically, the oil path flowsform a cooling fluid inlet port 328, along the length of the sleevevalve body 302 in a direction towards the proximal end 308 and into thecavity 324. Having circulated in the cavity 324, as shown by the dottedpath, the oil can exit in a region beyond the groove 325 (having beenable to flow through the above-mentioned radial space) and back out intothe cylinder block 320 through a cooling fluid outlet port 330. Absentsome sort of sealing structure or mechanism, such as for example theseal 326, it would be possible for oil to leak past the flange 322 andinto the port 306.

The seal 326 is ring-shaped and may be formed from metal or elastomerand can be sized to fit within the groove 325 and to protrude out of thegroove 325 to form a seal and running surface against a sealing surface332 of the stationary part 320. The seal 326 can be dimensioned and havea ring tension such that it provides a good contact against the outercontact (sealing) surface 332 to minimize oil leakage, while alsomaintaining sufficient tension against the flange 322 with an innercontact surface such that during reciprocating strokes, a small amountof oil can flow onto the outer contact surface 332 to ensure sufficientlubrication during the stroke. In general, oil will be in the areabetween the seal 326 and the cooling fluid outlet port 330 while thevalve is in its closed position (e.g. with the proximal end 308 incontact with the valve seat 304). The sealing surface 332 upon which theseal slides is therefore coated with oil when the sleeve valve is inthis position. In some implementations of the current subject matter,this coating of oil can be sufficient to insure proper lubrication ofthe sliding surface. This lubricating oil and any oil which is scrapedby the ring can be drained by provision of a suitable drain in thesleeve valve body 602. The configuration of such a drain would need toensure that cooling oil circulating through the cavity 624 as previouslydescribed was not picked up into the seal. For example, a verticalconfiguration (i.e. vertically in FIG. 3A or in the direction of thearrow 310 oriented along the length of the sleeve valve 600) for thedrain would minimize this happening. Such a drain is shown schematicallyin the diagram 350 of FIG. 3B. This figure shows a similar arrangementto FIG. 3A, but a flange 322 a differs from the flange 322 of FIG. 3A inthat it contains a series of vent holes 340. FIG. 3B is taken throughone of the vent holes 340, which extend in the direction of the arrow310 from a groove 325 a such that coolant can drain out into the coolantoutlet port 330.

A metal ring seal 326 can be designed to balance the amount of oilallowed to pass and the life of the sliding surfaces. Typically, a metalring seals against the outside sealing surface 332 and one of the sidesof the groove 325, but not simultaneously against both the sealingsurface 332 and the base of the groove 325. For this reason, a metal oilcontrol ring can employ tension to push the outer contact surface of thering out against the sealing surface 332. A spring arrangement or someother configuration that provides an expansive force in a directionparallel to the arrow 310 to push the seal 326 against the sides of thegroove 325 can also or alternatively be included. A conventional pistonring used to contain lubricating fluid around a piston from entering thecombustion chamber generally relies on gas pressure to push the pistonring out against the cylinder walls and down against the side of agroove to make the seal. In the seal configurations described here, ametal seal 326 can include two or more rings. In one example, a threepiece ring can include two thin rings and a spring between the two thinrings to push the two thin rings outwardly against the sides of thegroove 325. Some examples of use of such a seal will be discussed inmore detail below. A seal 326 constructed of an elastomer material canseal against the inner and the outer surfaces because of its ability tochange shape under compression, which can accommodate changes indistance between the two sliding surfaces that can result frommanufacturing tolerances, temperature differences during operation, etc.

While the seal 326 moves with the sleeve valve, in many cases there willbe some local relative movement between the seal 326 and the other partsof the sleeve valve during reciprocating strokes. For example, somedegree of movement of the seal 326 within the groove 325 is possiblewithin the scope of the current subject matter. In other words, the seal326 remains substantially stationary relative to the sleeve valve ingeneral and specifically relative to the flange 322.

In a second sleeve valve system 400 shown in FIG. 4, a spring 402 ispresent to assist with seating of a sleeve valve body 302 against thevalve seat 304. Such a spring can also be used in the configurationsshown in FIG. 3A and FIG. 3B. The sleeve valve body 302 has a flange322. In the configuration of FIG. 4, the flange 322 of FIG. 4 includes afirst groove 325A to accommodate a first seal 326A having a first sealinner contact surface and a first seal outer contact surface. The flange322 also includes a second groove 325B, disposed more distal from theproximal end 308 of the sleeve valve, to accommodate a second seal 326Bhaving a second seal inner contact surface and a second seal outercontact surface. An end region 327 of the flange 322 is shaped toaccommodate the two grooves 325A and 325B. The grooves 325A and 325B mayeach carry a seal of any of the types described above with respect toFIG. 3A and FIG. 3B. Alternatively, one groove may carry a seal of anyof the types described above with respect to FIG. 3A and FIG. 3B, whileanother carries a gas-control ring to minimize leakage of gaseousproducts past the sleeve valve body 302. One example of a possible gascontrol ring will be discussed below with reference to FIG. 9.

FIG. 5 shows a process flow chart 500 illustrating method features, oneor more of which can be included in an implementation of the currentsubject matter. At 502, a sleeve valve is cooled with a cooling fluid,in a manner as described above. The cooling fluid can be oil in at leastsome implementations. At 504, the sleeve valve is operated during acombustion cycle of an internal combustion engine in which it provides avalve function. During some time periods of the combustion cycle, thesleeve valve is stationary, and during other time periods it moves (in areciprocating motion), to open or close a port. At 506, the sleeve valveresists leakage of cooling fluid to the port by action of one or morering-shaped seals carried in a respective groove on the sleeve valve.Thus, the seal moves with the valve body or, in other words, remainssubstantially stationary relative to the valve body during thecombustion cycle. Thus its sealing function is optimized. This mayimprove oil consumption and durability relative to some stationary sealarrangements. Additionally, the seal is formed at a constant distancefrom a contact end of the sleeve valve, thereby avoiding a conditionthat can occur in previously available approaches in which the seal isperiodically exposed to elevated temperatures of the combustion chamber,for example when the sleeve valve is in an open position and theproximal, contact end of the sleeve valve is withdrawn to the vicinityof a stationary seal mounted on the engine block or some otherstationary part of the engine.

A ring-shaped seal made of one or more of a variety of materials,including but not limited to metal (e.g. steel or the like), anelastomer, etc., can be used as the seal 326, 326A, 326B. Thering-shaped seal may be generally ring-shaped but have a gap in aportion of the ring, to facilitate the correct tension and consequentpre-load in the ring relative to the sleeve valve. The ring-shaped sealmay be flat to provide optimal contact with the sides of the grooves325, 325A or 325B. An additional spring may be provided to enable thering to provide an appropriate level of force to operate as a seal andto allow lubrication as described above. The invention is not limited toa single ring but may include arrangements having multiple rings orother configurations such as spiral rings having, for example, 2-5 ormore turns.

A system consistent with implementations of the current subject mattercan include a sleeve valve including a valve body arranged to at leastpartially encircle at least one piston arranged to move in areciprocating manner. The sleeve valve and the at least one piston atleast partially define a combustion chamber of an internal combustionengine. The sleeve valve is moveable between an open position and aclosed position to control fluid flow through a port of the internalcombustion engine. The system can also include a substantiallyring-shaped seal carried in a groove on the sleeve valve in aconfiguration. During operation of an internal combustion engine thatincludes the sleeve valve, the substantially ring-shaped seal remainssubstantially stationary relative to the sleeve valve to resist leakageof coolant from the valve body to the port.

FIG. 6 shows an alternative sleeve valve assembly 600 illustratingfeatures consistent with one or more implementations of the currentsubject matter. A cross-section through a sleeve valve body 602 isdepicted. The sleeve valve body 602 is shown in a closed position,covering a port 306 (which can be an intake port, an exhaust port,etc.). In this position, the sleeve valve body 602 forms a gas seal witha valve seat 304 at a first end 608 of the sleeve valve 602. The firstend 608 is proximal to the valve seat 304. As shown in FIG. 6, the firstend 608 of the sleeve valve includes a gas assist feature similar tothose described in co-owned U.S. Pat. No. 7,559,298 and co-owned U.S.patent application publication no. US2012/0085309A1, the disclosure ofwhich is incorporated herein by reference.

The sleeve valve body 602 reciprocates to open and close the port 306,in a similar manner as discussed above with respect to the sleeve valvebody 302 of FIG. 3A and FIG. 3B. FIG. 7 shows the sleeve valve assembly600 in an open position, in which the port 306 is open i.e. not coveredby the sleeve valve assembly 600.

The sleeve valve body 602 can be formed as a hollow cylinder having aninside surface 612 and an exterior surface 614 and a length extending inthe direction of the arrow 610. A piston and a combustion chamber (notshown) are disposed in the interior 616 of the hollow sleeve valve body602. In other words, the sleeve valve body 602 at least partiallyencircles at least one piston and a combustion volume that expands andcontracts with motion of the at least one piston. A portion of theexterior surface 614 of the sleeve valve 602 distal from the valve seat304 can run against a cylindrical guide 618 disposed between this distalportion of the sleeve valve and a stationary part 620, which can be theengine block or other engine structure relative to which the sleevevalve body 602 moves.

The proximal end 608 of the sleeve valve can include a flange or lip 622spaced radially outward from the sleeve valve body 602. A cavity 624 canbe formed in the space between the exterior surface 614 of the sleevevalve body 602 in the region of its proximal end 608 and the flange 622.The flange 622 can extend a sufficient distance along the length of thesleeve valve body 602 to cover the port 306 and to enable formation of aseal against the stationary part 620. The flange 622 forms the exteriorsurface of the sleeve valve in this region of the sleeve valve andpartially surrounds the sleeve valve body 602. This part of a sleevevalve can be referred to as an “umbrella” structure. This umbrellastructure can have an exterior surface finish that has been engineeredto provide a sealing surface for sealing against a stationary seal 626mounted in the stationary part 620. Typically, the surface finished inthis way is hard enough to resist the abrasion from the seal 626 and hassmall surface features that can maintain a small amount of coolant, suchas oil, which lubricates the interface between the seal 626 and thesurface of the flange 622 as the sleeve valve body 602 moves. Steel andiron having a surface topology provided by a honing process are examplesof a suitable surface finish, but others could be contemplated by thoseskilled in the art. In one example, the honing can include a pattern ofshallow scratches that are narrow compared to the dimensions of thesleeve valve body 602 at that are aligned at some angle (e.g.±approximately 45°, ±approximately 30°, ±approximately 60°) relative tothe axis along which the sleeve valve reciprocates. During operation,such scratches can fill with oil to thereby create a sealing effectwhich can minimize transmission of oil past the sleeve valve body 602 tothe port 304 and which is also able to form a substantially gas-tightseal. In another example, the honing can include a pattern of surfacefeatures such as divots, depressions, channels, or the like. Surfacetopologies such as those described, as well as others that are alsowithin the scope of the current subject matter, can be formed byprocesses such as grinding, burnishing, bombardment with beads or othermaterials, sanding, laser treatment, etching, or other that might becontemplated by those skilled in the art.

The seal 626 is mounted in a stationary part 620 such as an engineblock, so it remains substantially stationary while the sleeve valveassembly 600 moves. In other words, the position of the seal 626relative to the moving sleeve valve body 602 varies as the sleeve valvemoves. For example, in FIG. 6, the seal 626 can be seen as contactingthe flange 622 some way along the flange from the proximal end 608 ofthe sleeve valve body 602, whereas in FIG. 7, the seal 626 can be seenas contacting the flange 622 close to the proximal end 608. The regionof the stationary part 620 where the seal is mounted is a small distance(relative to the length of the sleeve valve assembly 600) away from theport 306 in the direction of the arrow 610 i.e. along the length of thesleeve valve assembly 600. Thus in FIG. 7, the contact point is not atthe proximal end 608. This arrangement assists in keeping anylubricating coolant which is present between the surface of the flange622 and the stationary part 620 away from the port, although the contactpoint could be at the proximal end or closer to it in someimplementations. Whilst the seal remains substantially stationary, theremay also be some local relative movement of the seal 626 within theregion in which it is held in the stationary part 620. For example, somedegree of movement of the seal 626 within the stationary part 620 ispossible within the scope of the current subject matter.

The seal 626 can be an elastomeric seal, as described in co-owned USpublication no. 2012/0085309A1. However, durability may be improved ifat least a part of the seal 626 comprises a metal.

One possible design for the seal 626 is a ring arrangement as shown inFIG. 6 and FIG. 7. FIG. 8 shows an enlarged view 800 of the seal 626. Itincludes a first metal ring 650 disposed at the proximal side of theseal 626 and a second metal ring 652 disposed at the distal side of theseal 626. In various implementations, the rings 650, 652 may be formedfrom cast iron or steel or some other metal or metal alloy. The rings650, 652 can also or alternatively include a coating of a metal or analloy, such as for example molybdenum or chrome, to provide a hardsurface finish on the sealing surface of the ring or rings (e.g. thesurface of the ring that contacts with the sleeve valve body 602). Therings 650, 652 are shaped as flat cylinders and sit in a planesubstantially perpendicular to the arrow 610 i.e. to the length of thesleeve valve assembly 600. Having a substantially planar inner surfacefacilitates contact with the surface of the flange 622. However, thisprecise shape is not essential. The two rings 650, 652 may be identicalin shape and size or they may be different. The rings can optionally besplit. In one example the rings can be configured as one-piece with twonarrow regions for contacting the sliding surface of the sleeve valvebody 602. The internal geometries of the rings may cause or facilitatethe rings to be urged towards the sides 656 of the groove 656. The size,shape, material, curvature and possibly other aspects of theconfiguration of the rings is chosen such that they have a desired ringtension when fitted around a sleeve valve moving relative to thestationary part 620 in which the rings are held. They are accordinglypretensioned such that they maintain contact with the sleeve valve body602 on their inner circumferences. They exert a combined force againstthe sleeve body 602, which may have components of force from each of thetwo rings. Typical ring tension may be similar to that of a conventionalpiston ring, but, unlike a conventional piston ring which exerts anoutward force, the rings consistent with implementations of the currentsubject matter exert a force towards the center of the rings i.e. aradially inward force, resulting in a pressure on the sleeve valve body602.

The first and second rings 650, 652 can be separated by a biasingstructure 654, which may be a spring, and conveniently is a springwasher or other similar structure. The ring arrangement is fitted in agroove 656 in the stationary part 620. The groove 656 has a first side658, corresponding to the proximal end of the sleeve valve body 602 anda second side 660, corresponding to the distal end of the sleeve valvebody 602. Thus the first and second sides 658, 660 are substantiallyflat and substantially parallel to the first and second rings 650, 652when the ring arrangement is installed in the groove 656. The biasingstructure 654 tends to hold the first ring 650 against the first side658 and the second ring 652 against the second side 660. Thus the firstring 650 exerts a first lateral force on the first side 658 and thesecond ring 652 exerts a second lateral force on the second side 660.The arrangement of the biasing structure 654 between the two rings 650,652 thus urges the rings against the sides of the groove 656 and therebyimproves the effect of the seal 626 by improving the stability of therings 650, 652 when subject to forces arising from their contact withthe moving sleeve valve 600.

As the sleeve valve 600 moves from the open position of FIG. 7 to theclosed position of FIG. 6, the second ring 652 can scrape by at least asmall amount of lubricant (e.g. oil) as the surface of the flange 622moves against the second ring. This lubricant can be pushed back duringthe return stroke to the closed position and can flow back between theflange 622 and the stationary part 620 and out through the cooling fluidoutlet port 330. The first ring 650 will scrape additional lubricant.FIG. 6, FIG. 7, and FIG. 8 show that the groove 656 is open to a drainor vent 662 at the opposite end to that against which the flange 622moves. Thus any oil that is scraped by the rings 650, 652, andparticularly oil scraped by the first ring 650, can flow through thespring 654 to the back of the groove 656 and can then drain out of thegroove 656. Alternatively or additionally, one or both rings could beprovided with one or more holes and or grooves through which coolant candrain. The vent 662 feeds into the exit port 320, so that any drainedoil can flow away from the combustion chamber together with oil that hascirculated around the oil path defining piece, and eventually to theengine sump.

In examples consistent with the present subject matter where the seal isheld in a stationary part of the engine, the hottest region of thesleeve valve body 602 i.e. the proximal end 608 which closes the port306, will be closer to the seal at some times during an engine cyclethan it would be if the seal remained a fixed distance from the proximalend 608 as in examples such as those of FIG. 3A and FIG. 3B. Analternative or additional means of cooling the sleeve valve may beemployed to protect if from the heat of the proximal end 608 of thesleeve valve body 602. Provision for this could be made by means of anextra coolant path, for example in the form of an extra cavity, providedin the stationary part 620 in the region of the seal 626, such as behindthe seal. Two such cavities 664 a and 664 b are depicted in FIG. 6 andFIG. 7. Such cavities can be sized and positioned to fit on one or bothsides of the drain 662 and their shape can vary from the exemplaryschematic shape shown. Additionally or alternatively, in examples wherethe sleeve valve has an umbrella structure or some other internal cavityinto which a cooling material can be placed or can flow, sufficientcooling of the valve can be insured in this manner. In application ofthe present subject matter to a turbocharged engine, it may be desirableto provide both cooling of the stationary part 620 such as a cylinderblock and cooling of the sleeve valve 600 itself, in view of the higherpressure and temperature in the exhaust port as compared to a naturallyaspirated engine, although both types of cooling could be provided in anaturally aspirated engine if desired.

The arrangement of a seal 626 in a groove 656 as shown in FIG. 6, FIG.7, and FIG. 8 may be suitable for a naturally aspirated engine. FIG. 9shows view 900 of an alternative arrangement, which may be suitable fora turbocharged engine. FIG. 9 shows a seal 626 of the type as describedabove with reference to FIG. 6, FIG. 7, and FIG. 8. However, a distancefrom the seal 626 towards the proximal end of the sleeve valve body 602is disposed a further ring 950. The further ring 950 is disposed in asecond groove 952, which is sized and shaped for the ring 950 to fitsnugly therein. The further ring 950 may be made of metal and may be aflat, split ring. It is configured to have a ring tension which holds itagainst a moving sleeve valve 600 and its purpose is to form a gas seal.Particularly in a turbocharged engine, the manifold gas pressure mayassist in urging the further ring 950 against the sleeve valve and alsoagainst the sides of the second groove 952, thereby enhancing resistanceto gas leakage. The further ring 950 differs from, for example, aconventional piston ring that resists gas leakage because it is acompression ring which exerts a force inwards i.e. towards a center ofits circumference. By contrast, a conventional piston compression ringis arranged to exert a force outwards i.e. away from a center of itscircumference so as to urge an outer side of the ring against a cylinderwall.

It may be desirable to use a further ring 950 in a naturally aspiratedengine. It may also be useful to use one or two further rings such asthe further ring 950 in a turbocharged engine, in order to furtherimprove resistance to gas leakage. This approach can be desirable in aheavily turbocharged engine where the exhaust system pressure is veryhigh relative to the engine internal pressure.

In either of the arrangement of FIG. 6, FIG. 7, and FIG. 8 or that ofFIG. 9 or other arrangements having a combination of one or more oilseals and one or more gas seals, a valve spring such as the valve spring402 shown in FIG. 4 could be present.

The arrangements of FIG. 6, FIG. 7, and FIG. 8 or FIG. 9 can optionallybe used in examples where the seal is carried on the sleeve valve, suchas the arrangements shown in FIG. 3A, FIG. 3B, and FIG. 4. For example,the seal 326 in FIG. 3A and/or the seal 326 a in FIG. 3B could bereplaced by the seal 626 of FIG. 6, FIG. 7, and FIG. 8.

FIG. 10 shows a process flow chart 1000 illustrating method features,one or more of which can be included in an implementation of the currentsubject matter. At 1002, a sleeve valve is cooled and/or lubricated witha liquid, in a manner as described above. The liquid, which can haveeither or both of cooling and lubricating properties, can be oil in atleast some implementations. At 1004, the sleeve valve is operated duringa combustion cycle of an internal combustion engine in which it providesa valve function. During some time periods of the combustion cycle, thesleeve valve is stationary, and during other time periods it moves (in areciprocating motion), to open or close a port. At 1006, the sleevevalve resists leakage of the liquid to the port by action of one or moreseals exerting a radial force against the valve body of the sleeve valvei.e. a force directed co-linearly with a radius of the seal, thecylinder, the sleeve valve, etc. A suitable seal can include two ringswhich are biased apart from one another. The seal may be held in agroove and thus the rings may each be biased against one side of thegroove. The groove may be situated within a stationary part of theinternal combustion engine, such as an engine block or an oil-pathdefining piece. Thus, the seal and a valve body of the sleeve valve moverelative to one another during the combustion cycle.

It will be understood by those skilled in the art that features of thecurrent subject matter could equally well be applied to a sleeve valveoperating to open and/or close one or more ports in an engine in whicheach piston moves in its own cylinder. Furthermore, it is not essentialfor the sleeve valve to have an “umbrella” portion, but ratherembodiments of the invention are also applicable to the main body of asleeve valve not having a flange.

In the descriptions above and in the claims, phrases such as “at leastone of” or “one or more of” may occur followed by a conjunctive list ofelements or features. The term “and/or” may also occur in a list of twoor more elements or features. Unless otherwise implicitly or explicitlycontradicted by the context in which it used, such a phrase is intendedto mean any of the listed elements or features individually or any ofthe recited elements or features in combination with any of the otherrecited elements or features. For example, the phrases “at least one ofA and B;” “one or more of A and B;” and “A and/or B” are each intendedto mean “A alone, B alone, or A and B together.” A similarinterpretation is also intended for lists including three or more items.For example, the phrases “at least one of A, B, and C;” “one or more ofA, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, Balone, C alone, A and B together, A and C together, B and C together, orA and B and C together.” Use of the term “based on,” above and in theclaims is intended to mean, “based at least in part on,” such that anunrecited feature or element is also permissible.

The subject matter described herein can be embodied in systems,apparatus, methods, and/or articles depending on the desiredconfiguration. The implementations set forth in the foregoingdescription do not represent all implementations consistent with thesubject matter described herein. Instead, they are merely some examplesconsistent with aspects related to the described subject matter.Although a few variations have been described in detail above, othermodifications or additions are possible. In particular, further featuresand/or variations can be provided in addition to those set forth herein.For example, the implementations described above can be directed tovarious combinations and subcombinations of the disclosed featuresand/or combinations and subcombinations of several further featuresdisclosed above. In addition, the logic flows depicted in theaccompanying figures and/or described herein do not necessarily requirethe particular order shown, or sequential order, to achieve desirableresults. Other implementations may be within the scope of the followingclaims.

What is claimed:
 1. A sleeve valve assembly comprising: a sleeve valvehaving a valve body configured to at least partially encircle one ormore pistons that moves in a reciprocating manner on operation of aninternal combustion engine, the sleeve valve and the one or more pistonsat least partially defining a combustion chamber of the internalcombustion engine, the sleeve valve being configured to move betweenopen and closed positions to control fluid flow through a port thatopens to the combustion chamber; and a substantially ring-shaped sealconfigured to resist leakage of a liquid comprising coolant and/orlubricant past the valve body to the port, the substantially ring-shapedseal comprising at least one of: a) a ring carried in a groove recessedinto the valve body, and b) first and second rings disposed around thevalve body and biased apart from each other, the first and second ringsbeing disposed on a stationary part of the internal combustion enginesuch that the valve body moves relative to the first and second rings.2. The sleeve valve assembly of claim 1, wherein the ring and/or each ofthe first and second rings is formed of a metal.
 3. The sleeve valveassembly of claim 1, further comprising one or more compression ringsfor resisting leakage of gases in the combustion chamber and/or the portpast the sleeve valve.
 4. The sleeve valve assembly of claim 1, whereinthe sleeve valve reciprocates between the open and closed positionsalong a common axis with a piston of the one or more pistons.
 5. Thesleeve valve assembly of claim 1, wherein the substantially ring-shapedseal comprises the ring carried in the groove recessed into the valvebody, and wherein the seal exerts a radial force outward against thestationary part of the internal combustion engine.
 6. The sleeve valveassembly of claim 5, wherein the seal exerts a first force against afirst side of the groove and a second force against a second side of thegroove.
 7. The sleeve valve assembly of claim 6, wherein the sealcomprises a biasing structure that exerts the first and second forces.8. The sleeve valve assembly of claim 5, wherein the seal comprises boththe ring and an additional ring, and the ring and additional ring aresubstantially flat, split rings.
 9. The sleeve valve assembly of claim8, wherein the ring and the additional ring are separated by the biasingstructure.
 10. The sleeve valve assembly of claim 5, wherein the grooveis configured such that the material thickness of the valve body issubstantially the same at the groove as through a remainder of the valvebody.
 11. The sleeve valve assembly of claim 5, wherein the seal remainssubstantially stationary relative to the valve body as the sleeve valvemoves.
 12. The sleeve valve assembly of claim 1, wherein thesubstantially ring-shaped seal comprises the first and second ringsdisposed on the stationary part and around the valve body, and whereinthe first and second rings have respective ring tensions to exert aradial force inward against the valve body.
 13. The sleeve valveassembly of claim 12, wherein the first ring and the second ring areseparated by a biasing structure which biases them apart.
 14. The sleevevalve assembly of claim 12, wherein the first and second rings compriseflat, split rings having respective ring tensions arising from one ormore of their shape; size; curvature and material.
 15. The sleeve valveassembly of claim 12, wherein the stationary part comprises a groove inwhich the seal is installed and wherein the first ring is biased againsta first side of the groove and the second ring is biased against asecond, opposite side of the groove.
 16. The sleeve valve assembly ofclaim 15, wherein the stationary part further comprises an oil drainthrough which oil in the groove drains.
 17. A method comprising: movinga sleeve valve between open and closed positions to control fluid flowthrough a port of an internal combustion; and resisting leakage of aliquid comprising coolant and/or lubricant past a valve body of thesleeve valve to the port, the resisting being performed at least in partby a substantially ring-shaped seal comprising at least one of: a) aring carried in a groove recessed into the valve body, and b) first andsecond rings disposed around the valve body and biased apart from eachother, the first and second rings being disposed on a stationary part ofthe internal combustion engine such that the valve body moves relativeto the first and second rings.
 18. The method of claim 17, furthercomprising resisting leakage of gas past the sleeve valve.
 19. Themethod of claim 17, wherein the sleeve valve reciprocates between theopen and closed positions along a common axis with a piston of the oneor more pistons.
 20. The method of any of claim 17, wherein thesubstantially ring-shaped seal comprises the ring carried in the grooverecessed into the valve body, and wherein the seal exerts a radial forceoutward against the stationary part of the internal combustion engine.21. The method of any of claim 17, wherein the substantially ring-shapedseal comprises the first and second rings disposed on the stationarypart and around the valve body, and wherein the first and second ringshave respective ring tensions to exert a radial force inward against thevalve body.
 22. The method of claim 21, further comprising drainingliquid out of a groove in the stationary part in which the seal isdisposed.